Koli, Dipika, Ketaki Utpat, Unnati Desai, and Nandakishore Arun. “Coexistence of Upper Airway Obstruction on Spirometry With Flow Volume Loop in Patients With Chronic Obstructive Pulmonary Disease”. Monaldi Archives for Chest Disease 96, no. 4 (October 27, 2025). Accessed November 1, 2026. https://www.monaldi-archives.org/macd/article/view/3531.